The Page Content particle displays content assigned to a given page. For example, if you have articles that you would like to have appear on your home page amongst your other particles and modules, you can do so by including the Page Content particle in your layout.
The Page Content particle itself doesn't have any specific particle settings. It's simply a portal by which any content you have assigned to that page (or type of page) is displayed. You can still, of course, use the Block settings tab to refine the look and presentation of the content block as you would any other particle.